I had the previous version of Five Icon Dock installed and uninstalled it today to install the new version of Five Icon Dock for iOS 7. Somewhere in the middle of all that, the 5th icon on my dock (Music app) somehow vanished! I've tried everything I can to get it to reappear on the Springboard but it's just not happening.

bump....same thing happened to me. I had the facebook icon down there as my fifth icon. removed the Five Icon Dock (to install the new iOS7 one) and now the facebook icon is missing. the only way i can access it is by going into the app store, searching for facebook and clicking "open" to open it. I've reinstalled five icon dock to see if it reappeared but still hidden.

alright....found a workaround.

install sbsettings

in sbsettings options, find the option to hide your icons. then select to hide the missing app (even if its missing). respring...go back there and then unhide it. after respringing the second time my missing icon is back. what a pain in the ***.